The invention is generally in the field of nanostructures and relates to localized plasmon transducers and methods of their fabrication, and may be used in the field of chemical and biological sensors.
Metal islands present unique optical and electronic properties, notably different from those of the bulk material. The special optical phenomena, associated with metal clusters (e.g., gold, silver, copper), may be attributed to excitation of localized surface plasmons (SPs) and observed as strong light scattering, intense light absorption, and local electromagnetic field enhancement. The localized surface plasmon resonance (LSPR) extinction band (shape, amplitude, frequency of maximum extinction) of an ensemble of Au or Ag nanoislands depends on the particle size, shape and spacing, as well as on the effective refractive index of the surrounding medium. The latter forms the basis for sensing applications based on refractive index change at the nanoisland-medium interface as a consequence of analyte binding. Optical transducers with LSPR band may be used in relatively simple and low-cost optical systems for biological and chemical sensing.